No problem! When you create your account, these are added at that point. If you change them, or have additions, this is very easy to do.

Just connect your account, then click 'edit profile'

Scroll down to the boxes that contain details about your organization.

Then you can choose your 'Head Office' country - usually where you are registered as a nonprofit.

And your 'Active Countries' - where you can choose as many countries as you wish.

Don't forget to scroll down the page after you have made your changes and 'Submit Changes' - otherwise they will not be saved.